The invention relates to an integrated light source comprising a first light-emitting element and a second light-emitting element.
An integrated light source of the type mentioned in the opening paragraph is known from WO 99/53236. In this document a description is given of a color illuminating unit comprising a lamp which, in operation, is connected to the mains voltage, and a plurality of blue, green and red light-emitting elements which, in operation, are operated at a voltage that is low as compared to the rated mains voltage.
A drawback of the known integrated light source resides in that said integrated light source cannot be operated in a convenient way.
It is an object of the invention to provide an integrated light source of the type mentioned in the opening paragraph, which can be operated in a more convenient way.
This object is achieved in accordance with the invention in that,
the first light-emitting element has, in operation, a comparatively high light output,
the second light-emitting element has, in operation, a light output which is relatively low in comparison with that of the first light-emitting element, and
the integrated light source is further provided with a control mechanism comprising means that are responsive to sequential changes in voltage, so that, at the user""s choice, at least one of the light-emitting elements can be switched on or off.
The use of the control mechanism in accordance with the invention enables a user of the integrated light source to sequentially change the voltage through the integrated light source by making use of a light switch that is situated at a distance from the light source. This has the advantage that, even if the integrated light source in accordance with the invention is provided in places that are difficult to reach, switching between the different lighting states of the integrated light source can still be carried out in a convenient way. If the known integrated light source is provided in a room in such a manner that the light source is difficult to reach, for example because the light source is in a comparatively high position (for example attached to, or in the vicinity of the ceiling of the room), changing the voltage through the integrated light source at the location of said integrated light source is inconvenient. Auxiliary means (for example a stepladder) may be needed to switch between the different illumination states of the integrated light source. This may give rise to risky situations. In addition, in operation, the integrated light source may be hot, which may lead to problems when the user touches the integrated light source to change the voltage through the light source in order to switch on and off the light-emitting elements. By suitably using the light switch that is known per se, which is provided, for example, on a wall of the room or is switched, for example, by means of a remote control, the control mechanism in accordance with the invention enables the desired light level to be attained.
In the description of the invention, the expression xe2x80x9csequential changes in voltagexe2x80x9d is to be taken to mean that the voltage level is changed, for example, by sequentially switching on or off the voltage through the integrated light source. The voltage can be changed in an alternative way, for example, by reducing the voltage through the integrated light source to at least 80% or to 50% of the voltage, for example, by using a dimmer switch.
The control mechanism comprises means which are known per se for reacting to a certain sequence of changes in the voltage through the integrated light source. Said means comprise, preferably, a comparatively straightforward electronic circuit with a so-termed toggle-switch, which is responsive to, for example, the sequential switching on and off of the voltage. Dependent upon the time that elapses between changing the state of the light switch and returning the light switch to the original state, the settings of the control mechanism determine whether one or both integrated light-emitting elements will start emitting light.
The use of the control mechanism in combination with the application of a first light-emitting element having a comparatively high light output and a second light-emitting element having a comparatively low light output has the advantage that the integrated light source can be used as a normal lamp and as a so-termed night lamp. Night lamps are used, inter alia, as orientation lighting (for example for security purposes) and as a light-emitting element for increasing the sense of comfort or safety, for example in a nursery. A drawback of the night lamp that is known per se resides in that it generally has a very low light output, i.e. the night lamp itself is visible when it is switched on, but it spreads comparatively little light to its surroundings. The use of an integrated light source as a night lamp has the advantage that the light output in the night position is comparatively higher than that of the known night lamp, so that a satisfactory orientation in relation to the surroundings is possible.
An important advantage of the integrated light source in accordance with the invention resides in that the integrated light source is retrofit for an existing lamp, and further adaptations to bring about the switching states of the integrated light source are not necessary. At the location where a normal lamp is provided in a room, this lamp is removed from the luminaire and substituted with the integrated light source in accordance with the invention. The switching possibilities do not require any further adaptation; even the light switch present in the room does not have to be adapted.
A preferred embodiment of the integrated light source is characterized in that the first light-emitting element comprises a low-pressure mercury vapor discharge vessel and the second light-emitting element comprises at least one light-emitting diode.
In general, it is rather difficult to satisfactorily or sufficiently dim a low-pressure mercury vapor discharge lamp. As a result, a low-pressure mercury vapor discharge lamp is comparatively unsuitable for use as a night lamp. In addition, it has been found that even in the dimmed state of the low-pressure mercury vapor discharge lamp, the light level generally is too high, so that said discharge lamp cannot suitably be used as a night lamp. It is convenient to combine the low-pressure mercury vapor discharge lamp with one or more light-emitting diodes (LEDs). LEDs have a comparatively low light output, are cheap in terms of energy consumption and have a very long service life. For the light-emitting diodes use can be made of white LEDs or colored LEDs, for example red, green, orange and/or blue LEDs. According to the desired application of the integrated light source, LEDs of various colors can be combined in an integrated light source. By switching off the low-pressure mercury vapor discharge lamp by means of the control mechanism, the LEDs having a comparatively low light output serve as a night lamp or as orientation lighting.
An alternative preferred embodiment of the integrated light source in accordance with the invention is characterized in that the first light-emitting element is surrounded by an outer bulb, the second light-emitting element being situated in the space between the first light-emitting element and the outer bulb. The outer bulb protects the first light-emitting element as well as the second light-emitting element, for example a plurality of LEDs. The second light-emitting element preferably comprises four LEDs.
In a further alternative embodiment of the integrated light source, the LEDs are directly provided on an electronic circuit in the housing, and an outer wall of the housing is provided with small apertures from which the LEDs project.
Preferably, the first light-emitting element comprises a compact low-pressure mercury vapor discharge vessel, and the second light-emitting element comprises at least one light-emitting diode. The invention particularly relates to a combination of a compact low-pressure mercury vapor discharge vessel with an outer bulb, with one or more LEDs being situated in the space between the outer bulb and the low-pressure mercury vapor discharge vessel. In this embodiment, the integrated light source has the appearance of an incandescent lamp, so that it is also referred to as an xe2x80x9cincandescent lamp look-alikexe2x80x9d, the compact low-pressure mercury vapor discharge vessel and a number of LEDs being situated on the inside of the integrated light source, and being capable of being selectively switched on or off by using the switching properties of the control mechanism. The control mechanism is preferably provided in the housing of the integrated light source.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.